This batch of lights was on test for 3000 hours – the equivalent of about seven months, assuming five hours' usage per day. Most performed reasonably well, but some samples have failed already - well short of their claimed lifespan - and some have noticeably faded in light output. We've now stopped this test and will be starting a new batch of lights soon.

LEDs look set to replace CFLs over the next few years as LED lamp technology improves, prices head downwards and concern about the mercury content of CFLs increases. However, LEDs are still comparatively expensive to buy, and those on test range in price from about $20 to $95 per globe. Also, there are few, if any, models in the standard bulb shape with very high light output (more than 1300 lumens, or 100W equivalent).

Rapid switching

CFLs are susceptible to failure if switched on and off too frequently, while LEDs, in general, are not. After testing our previous batch of lamps we put them through a rapid switching test. This involved switching them on and off continuously for 454 hours (almost 19 days) on a cycle of 30 seconds off and four-and-a-half minutes on.

Of the seven CFL models in that test, three suffered failures and of the eight LED models, only one suffered a failure.

We also put the recent batch through the same test. Again, the CFLs suffered the most burnouts, with most of them failing after several days of rapid switching. However, some LEDs also failed; one Verbatim and two of the Crompton Lighting XL-LED Opal ECO 10W. Interestingly, the Viribright LEDs began showing small red areas of light – maybe not enough to be noticeable if inside a frosted glass light fitting, but quite obvious when looking at the naked bulb and possibly a sign that this model doesn’t cope well with rapid switching.

LEDs clearly have an advantage over CFLs when it comes to rapid switching, although it’s best to avoid switching lights on and off too often. If you’re going in and out of a room several times in a short period (say 15 minutes), you’ll probably get better life from the light by keeping it on for the duration rather than switching it on and off each time. Where you have less control over a light’s switching pattern, such as with a motion-activated security light, an LED or halogen lamp is likely to last a lot longer than a CFL.

Video: CFLs

How does CHOICE test compact fluorescent lamps?

Note: most people probably still refer to CFLs and incandescents as "light bulbs", and think of a "lamp" as the light fitting on their bedside table. In fact, as pointed out by CHOICE members in the comments, "lamp" is the technically correct term for what we used to call light bulbs. We use both terms in this report.

How we test

Our test is based on the Australian Standard for self-ballasted lamps. The lamps on test are a mix of screw and bayonet fittings; all are “warm white”, but wattages vary. Our tester, James Thomson, installs 10 samples of each model in a rig of 150 light fittings, and burns them in for 100 hours. The lights are then put into a continuous switching cycle of 165 minutes on, then 15 minutes off, so they are on for a total of 22 hours per day.

Light output James measures the light output of the lamps after the 100-hour burn-in, then again after 1000 and 3000 operating hours.

Switch-on time is the time taken to start giving out light. In our test of CFLs in 2000, we found some took up to three seconds to activate. However, all the lamps in recent tests activated almost instantly, so James hasn’t measured the actual times.

Warm-up time shows the time taken to reach 80% of maximum brightness. CFLs usually take about 30 seconds or less, which is acceptable but still much slower than incandescent or LED lamps, which reach maximum brightness almost instantly. Some CFLs have long warm-up times of several minutes; this doesn't necessarily mean they are noticeably dim to start with, but rather that they can take a long time to stabilise at their maximum light output. LED lamps switch on immediately at maximum brightness then dim a little over the next few minutes (not enough to be noticeable to the naked eye).

Failure rate James regularly checks to see if any lamps have failed (either dying completely or dimming so much that in normal usage you’d replace them). Claimed life expectancy for CFLs typically ranges from 6000 to 15,000 hours; LED lamps claim 20,000 hours or more (often 35,000+).